Depressive conditions are not uncommon during the lifetime of asthma patients and occur at higher rates than in the general population. In particular, the prevalence of psychiatrically diagnosed depression is estimated to be 13 to 16% (lifetime rate, 40%), while the prevalence of other depressive conditions, variably termed depressive symptoms, depressed mood, and depressive disorders, is higher, ranging from 1 to 66% depending on the method of measurement, the definition of depressive condition, and characteristics of the sample.
Depression and asthma have a complex reciprocal relationship, with each condition capable of potentiating the other. For example, more asthma symptoms can lead to worse psychological outcomes, such as worse mood, and depressive conditions can lead to worse asthma outcomes, such as worse health-related quality of life and more urgent asthma resource utilization. These outcomes also are the result of more severe asthma and poorly controlled asthma. It is therefore likely that depressive conditions influence outcomes by affecting asthma severity and control.
Asthma severity refers to the long-term nature of asthma as a chronic illness. Asthma control refers to the short-term character of asthma with its potential waxing and waning pattern. Although correlated, severity and control are distinct parameters that can be measured independently. For example, severity can be measured by prior hospitalizations and the need for maintenance medications, while control can be measured by current symptoms and the need for rescue medications. However, to provide a more comprehensive picture, severity and control should be reported as composites of several variables using validated scales., These scales also facilitate assessing variables that impact severity and control, such as demographic characteristics, medication adherence, body mass index, smoking status, and depressive conditions.
Most studies reporting associations with asthma severity and control have assessed depressive conditions with patient-reported surveys. Only a few small studies have considered severity and control contemporaneously when major depression was diagnosed based on formal psychiatric evaluation, There are no studies, however, assessing relationships between depressive conditions described clinically by primary care physicians and asthma severity and control. Given that most patients receive both their asthma and mental health care from primary care physicians, diagnoses made by these physicians are critical in order for patients to be treated for both disorders. Therefore, the objectives of this crosssectional analysis were to assess patient-reported depressive symptoms and physician-reported depressive disorders in relation to asthma severity and control.